Cronbach's alpha measures what aspect of a scale?

Cronbach's alpha is a statistical measure used to assess the reliability of a scale, specifically the internal consistency of a set of items that are intended to measure a single construct. It evaluates how closely related the items in a scale are, indicating whether they yield similar results under consistent conditions. A high Cronbach's alpha value suggests that the items correlate well, meaning they are likely measuring the same underlying concept reliably.

Understanding reliability is crucial in research as it determines the consistency and stability of the measurement tool over time. If a scale has high reliability, researchers can confidently use it to infer that scores reflect true differences in the construct being measured, rather than inconsistencies due to measurement error. This is essential for ensuring the integrity of research findings and their applicability in psychology practice.